1. Field of the Invention
This invention relates to methods of making synthetic racing and sporting surfaces, particularly horse racing tracks, and methods of improving existing sporting surfaces.
2. Background
So-called synthetic surfaces have been used in competitive sport for several decades. In general, these are composite materials with varying amounts of cushion, and are installed as either a “roadbed” (type 1, track and field), as loose fill (type II), or as synthetic turf (type III). As opposed to fixed synthetic track surfaces (type I), such as those used in human racing tracks for track and field events, which are permanently installed and cannot be manipulated once installed, synthetic animal racing tracks (type II) are generally made of a softer and more workable material, which can easily be tilled, mixed and rolled back into place, much like a natural dirt surface. Several attempts have been made at formulating workable synthetic track surfaces of type II, but prior art compositions have had major drawbacks.
Current type II synthetic racing tracks, in general, are made of a combination of an inorganic substrate such as sand, various additive solid materials to impart elasticity, cushion or cohesiveness, and a binder material that promotes adhesion between the solid materials in the mixture. The use of fibers to promote cohesion in a racing surface was first disclosed by Armond (Armond, Victor J., U.S. Pat. No. 4,819,933, 1989), where a surface for equestrian use is formed using a mixture of sand and straight polymeric fibers. The fibers hold the sand together under the weight of travelers. Malmgren et al. (Malmgren, Robert C., Cipra, Jan and Umlauf, Edward L., U.S. Pat. No. 5,020,936, 1991) disclose an animal running surface composition composed of earthen material mixed with rubber particles. Similar compositions using binders were introduced about the same time. Binders, in general, are intended to make the heterogeneous mixtures of solids hold together and form a cohesive and consistent mixture. To date, binder technology for Type II synthetic surfaces has been limited to adding various waxes or rubber/oil mixtures to the inorganic substrates. Prior art binder materials only weakly associate with the inorganic substrates, and binding efficiency is influenced greatly by environmental conditions, such as temperature and moisture content. Several of these prior art surfaces have been referred to as “all-weather surfaces”. However, this has been found to be overly optimistic in real world installations.
Examples of polymer in oil types of binders are now well established in the prior art, but a highly representative example is taught by Hawkins, et al. (U.S. Pat. No. 4,792,133, 1988), who introduced a substitute ground surface material consisting of a substrate which was treated with ethylvinylacetate co-polymer dissolved in oil, preferably a soft grease. Alternate polymers disclosed by Hawkins include polystyrene, nylon or PVC. Hawkins and company later disclosed several further innovations, including the use of styrene-co-butadiene rubber in an oil or soft grease (Hawkins et al., U.S. Pat. No. 4,852,870, 1989). Dachtler et al. (Dachtler and Hawkins, Reissue U.S. Pat. No. 34,267, 1993) disclose much the same invention as the Hawkins surfaces previously disclosed.
Macke, on the other hand, has demonstrated a cushioned track surface for sporting events comprised of superposed courses of materials (Macke, Anthony V., U.S. Pat. No. 4,830,532, 1989), including a binding course made of shredded paper. The various materials are layered, one atop the other, each providing a discreet function in the performance of the track.
Bearden and Kottle (Bearden, Charles and Kottle, Sherman, U.S. Pat. No. 5,455,295, 1995) describe a racetrack surface including a synthetic polymer component, a warm hydrocarbon oil fluid, and a particulate material such as sand. The composition additionally incorporates carbon black to improve weatherability and a rakeability promoter to improve rakeability. Bearden continued to teach a substitute ground surface (Bearden, U.S. Pat. No. 5,559,166, 1996) containing sand and a binder comprising amorphous polyolefins or alpha-olefin interpolymers dissolved in a low aromatic oil.
Opfel discloses a soil amendment of a running surface for animal competition where clay granules are used as a binder for sand surfaces (Opfel, U.S. Pat. No. 6,810,831 B1, 2004), but this is no different than traditional sand and clay mixtures often referred to as “American Dirt”, used as surfaces for many American horse racing tracks.
Hawkins teaches methods of dust control and soil stabilization employing a binder consisting of polyolefins dissolved in carboxylic acids (Hawkins et al. U.S. Pat. No. 7,081,270 B2, 2006) or polyolefins and cyclic organic compounds dissolved in carboxylic acids (Hawkins et al., U.S. Pat. No. 7,074,266 B2, 2006).
Another polymer in oil binder is disclosed by Pearse (Ian Pearse, U.S. Patent Application US 2008/0017826, 2008), where the polymers ethylene propylene and styrene butadiene dissolved in oil are blended with a particulate containing composition.
Tracks that use wax as a binder are also described in the prior art. The best example is provided by Michael Dickinson (Dickinson, U.S. Pat. No. 5,961,389, 1999), where he describes a sport surface containing a mixture of sand, polyolefin fibers, polyolefin particles, tire fibers and a coating of wax to bind the materials together.
Hubbs has more recently described a surface material particularly suited for non-turf baseball field applications such as the pitcher's mound and base paths comprising clay, wax and sand, with a putty-like consistency.
Prior art binders are known to soften at higher temperatures and lose performance, causing the animals to labor harder to maintain speed. Conversely, at lower temperatures, particularly at freezing temperatures, prior art track surfaces become very firm, and can freeze. Sometimes the frozen surfaces become loose and the various components separate from each other. Surfaces lacking sufficient hydrophobicity or drainage are even more prone to freezing. The prior art binders often fail completely at freezing temperatures, no longer providing an adhesive effect, and allowing the solids to separate catastrophically. The wide variability and unpredictability of performance of prior art surfaces with changing environmental conditions has been a chronic problem. Also, the waxes, oils and polymers used in prior art surfaces tend to be highly susceptible to degradation by several pathways, and are made useless over time, requiring additional binder to be added periodically.
The present invention is a binder for sporting surfaces, which greatly improves their performance and extends their working temperature range, and which solves the aforementioned problems with prior art surfaces. Surfaces made according to the present invention maintain optimum performance over a much wider temperature range, are more water repellent, and are more resistant to environmental, chemical and mechanical degradation than prior art surfaces.